Deformation-compensating machine having a suspension comprising three balls



Filed Feb. 15, 1960 June 1965 J. PETTAVEL 3,190,173

DEFQRMATION'COMPENSATING MACHINE HAVING A SUSPENSION COMPRISING THREE BALLS 2 Sheets-Sheet l a 23 FIG. 1

June 22, 1965 PET EL 3,190,173

J. TAV DEFORMAIION-COM E SAT NG MACHINE VING A SUSPENSION MPRISING THREE A LS 6 Filed Feb. l5, l9 0 2 Sheets-Sheet 2' UnitedStates Patent A machine frame carrying a movable member is deformed by the varying positions assumed by said member, in particular by its varying position with reference to the point through which said frame rests on its pedestal. Such deformations are transmitted, sometimes with a certain amplification to various members rigid with the frame, for instance to uprights carrying measuring instruments.

The present invent-ion has for its object a precision machine, particularly a comparator wherein the deformations of the frame and the transmission of said deformations are reduced to a particularly small amount.

According to my invention, the machine includes a frame carrying through three points of support at least one intermediate member carrying in its turn a movable member.

The accompanying drawings illustrate by way of example a preferred embodiment of the invention. In said drawings:

FIG. 1 is a general elevational view of said embodiment and FIG. 2 is a corresponding plan view;

FIG. 3 is a cross-section through line m in of FIG. 1;

FIG. 4 is a view on a larger scale of a detail of FIG. 3;

FIGS. 5, 6 and 7 are cross-sections on a larger scale through lines V-V, VI-VI and VIIVII respectively of FIG. 2. v a

The comparator illustrated in the drawings includes a lower frame 1 or base member 1 supported by three feet 2 on a pedestal 3 and including two uprights 4 and 4a.

The lower frame 1 carries by means of three balls 5, 6 and r 7 a stationary upper table-carrying frame a bed 8 over which is guided a longitudinally slidable table or carriage 9. To said table 9 is secured a rule-carrying bar 10 on which rest two standard rules 11 and 12. The vertical and transverse adjustment of said bar10 is controlled by the corresponding hand wheels 13 and 14.

The two uprights 4 and 4a of the base member 1 carry by means of three further balls 15, 16 and 17 (FIG. 2) a stationary cross-member 18 having a slideway movably supporting two sliders 20 and 21 provided each with a photoelectric microscope 22 and23 respectively. An inrterferometer 24 serves for the measuring operations.

The different movable members of the machine are controlled by transmission rods actuated by suitable actuating means controlled from a control desk 25. The machine is fitted inside an air-conditioned room, the walls of which are illustrated only in part.

The mounting of the balls 5,6 and 7 supporting the upper table-carrying bed 8 is illustrated in FIGS. 5, 6 and 7 respectively. The'ball is held fast between two frustocones 26 machined in plates 27 screwed into recesses formed in the lower frame 1 and in the upper table-carrying bed 8 respectively. The ball 6 is held between two grooves 26 aligned with the ball 5 and it is thus provided ice with one degree of freedom. Lastly the ball 7 is provided with two degrees of freedom'since it is fitted between two parallel plane surfaces formed on the cooperating frames 1 and 8.

The frame or base member 1 is thus permanently subjected to three vertical forces of which a shifting of the carriage modifies the magnitude without modifying their direction. By inserting the balls in accurate vertical registry with the feet 2, it is possible to avoid any overchange which might lead to deformation of the frame 1 by changes in load distribution by movement of the carriage 9.

The stationary cross-member 18 is provided with two lateral noses 30 each entering one of the corresponding recesses 31 provided at the upper ends of the uprights and inside which the balls 15 and 16 are held. The ball 15 is held fast between two frustocones while the second ball 16 is held between two grooves aligned with said first ball 15. A plate 32 rigid with the underside of the cross-member 18 engages the third ball 17 fitted permanently inside a recess 33 formed in the vertical surface 34 of the upright 40 and held therein by a ring 35 (FIG. 4). The two balls 15 and 16 take the weight of the cross member 18 and transmit consequently to each upright a vertical force, the magnitude of which varies according to the position of the sliders while their direction remains unvarying. The torque arising in the cross-member 18 is taken by the balls 15 and 17 and its value remains constant since the shifting of the sliders 20 and 21 is parallel with the axis connecting the centers of the two balls 15 and 16.

What I claim is:

1. In high precision apparatus, the combination of a rigid base member, three feet supporting said base member on a foundation, a column structure comprising at least one column extending up from said base member, a superstructure carried by said column structure, at least one operating unit carried by said superstructure, means for moving and guiding said opera-ting unit on said superstructure, a stationary bed overlying said base member, means supporting said bed on said base member, a work carriage movably carried by said bed and adapted to support work for presentation to said operating unit, means 7 for moving said carriage and for guiding said carriage on said bed, said supporting means consisting of three balls disposed between said bed and base member and transmitting to said base member the entire weight of said bed, carriage and work, and means positioning said balls at all times in accurate vertical register respectively with said three feetsupporting said base member, whereby any deformation of said bed caused by the shifting of weight resulting from movement of said carriage is not transmitted to said base member nor to said column structure, superstructure and operating unit.

2. Apparatus according to claim 1, in which said bed and base are provided with means confining a first one of said balls against horizontal movement relative to said .bed and base, means guiding a second of said balls for horizontal movement only in the direction of a line extending between said first and second balls and parallel plane horizontal bearing surfaces engaging the third of said balls.

3. Apparatus according tov claim 1, in which said column structure comprises two columns extending up from said base member andsaid superstructure comprisesa, cross-member, and in which three independent single balls fitted between said columns and said cross member constitute the sole support for said cross-member. a

4; Apparatus according to claim 3, in whichrsaid columns'and cross-member are provided withmeans confining one of said last-mentioned balls againstrmovement relative to said columns and cross-member, means guiding a second of said balls for rolling movement only in the direction of a lineextending between said first and second halls and parallel. plane surfaces engaging the third of said last-mentioned balls.

4 i V References Cited by the Examiner 1 UNITED STATES PATENTS 1 6/17 Macdon-ald. 7 1,798,634 3/31 Scha fer 88 .-39 2,387,440 .10/45 'Guellich et al. 83-39'X 2,703,505 3/55 Senn 88 -14 '7 2,860,930 11/58 ,Schafranik ,308 6 2,912,761 i 11/59 Woodward et a1.

10 JEWELL H. PEDERSEN, Primary Examiner.

' EMIL S. ANDERSON, Examinen, 1 

1. IN HIGH PRECISION APPARATUS, THE COMBINATION OF A RIGID BASE MEMBER, THREE FEET SUPPORTING SAID BASE MEMBER ON A FOUNDATION, A COLUMN STRUCTURE COMPRISING AT LEAST ONE COLUMN EXTENDING UP FROM SAID BASE MEMBER, A SUPERSTRUCTURE CARRIED BY SAID COLUMN STRUCTURE, AT LEAST ONE OPERATING UNIT CARRIED BY SAID SUPERSTRUCTURE, MEANS FOR MOVING AND GUIDING SAID OPERATING UNIT ON SAID SUPERSTRUCTURE, A STATIONARY BED OVERLYING SAID BASE MEMBER, MEANS SUPPORTING SAID BED ON SAID BASE MEMBER, A WORK CARRIAGE MOVABLY CARRIED BY SAID BED AND ADAPTED TO SUPPORT WORK FOR PRESENTATION TO SAID OPERATING UNIT, MEANS FOR MOVING SAID CARRIAGE AND FOR GUIDING SAID CARRIAGE ON SAID BED, SAID SUPPORTING MEANS CONSISTING OF THREE BALLS DISPOSED BETWEEN SAID BED AND BASE MEMBER AND TRANSMITTING TO SAID BASE MEMBER THE ENTIRE WEIGHT OF SAID BED, CARRIAGE AND WORK, AND MEANS POSITIONING SAID BALLS AT ALL TIMES IN ACCURATE VERTICAL REGISTER RESPECTIVELY WITH SAID THREE FEET SUPPORTING SAID BASE MEMBER, WHEREBY ANY DEFORMATION OF SAID BED CAUSED BY THE SHIFTING OF WEIGHT RESULTING FROM MOVEMENT OF SAID CARRIAGE IS NOT TRANSMITTED TO SAID BASE MEMBER NOR TO SAID COLUMN STRUCTURE, SUPERSTRUCTURE AND OPERATING UNIT. 